Reheat operation for heat pump system

Abstract

A heat pump system includes a refrigerant circuit that has a compressor, a first heat exchanger, a second heat exchanger, a reheat heat exchanger, a modulating valve, and a reversing valve. The reversing valve is configured to transition between a first configuration to direct refrigerant from the compressor toward the modulating valve and a second configuration to direct the refrigerant from the compressor toward the first heat exchanger. The heat pump system also includes control circuitry configured to concurrently maintain the reversing valve in the first configuration and adjust a position of the modulating valve to direct a first portion of the refrigerant from the modulating valve to the second heat exchanger and a second portion of the refrigerant from the modulating valve to the reheat heat exchanger based on an operating mode of the heat pump system.

The invention claimed is: 
     
       1. A heat pump system, comprising:
 a refrigerant circuit comprising a compressor, a first heat exchanger, a second heat exchanger, a reheat heat exchanger, a modulating valve, and a reversing valve, wherein:
 the reversing valve is configured to transition between a first configuration to direct refrigerant from the compressor toward the modulating valve and a second configuration to direct the refrigerant from the compressor toward the first heat exchanger; 
 the modulating valve is configured to adjust between a first position, a second position, and a plurality of intermediate positions between the first position and the second position; 
 the modulating valve is configured to direct a first portion of the refrigerant received from the reversing valve to the second heat exchanger and a second portion of the refrigerant received from the reversing valve to the reheat heat exchanger, in parallel with one another, in each intermediate position of the plurality of intermediate positions; and 
 
 control circuitry configured to control operation of the reversing valve and the modulating valve in a modulating reheat mode of the heat pump system, and, in the modulating reheat mode, the control circuitry is configured to maintain the reversing valve in the first configuration, such that the refrigerant is received at the modulating valve from the reversing valve, and to adjust a position of the modulating valve to adjust a first amount of the first portion of the refrigerant directed to the second heat exchanger and adjust a second amount of the second portion of the refrigerant directed to the reheat heat exchanger. 
 
     
     
       2. The heat pump system of  claim 1 , wherein the control circuitry is configured to maintain the reversing valve in the second configuration and control the modulating valve to direct the refrigerant received at the modulating valve from the second heat exchanger to the reversing valve in a heating mode of the heat pump system. 
     
     
       3. The heat pump system of  claim 1 , wherein:
 in the first position, the modulating valve is configured to block flow of the refrigerant to the reheat heat exchanger; and 
 in a heating mode of the heat pump system, the control circuitry is configured to maintain the reversing valve in the second configuration and adjust the modulating valve to the first position. 
 
     
     
       4. The heat pump system of  claim 1 , wherein the control circuitry is configured to adjust the position of the modulating valve to adjust the first amount of the first portion of the refrigerant and the second amount of the second portion of the refrigerant based on an operating parameter of the heat pump system in the modulating reheat mode of the heat pump system. 
     
     
       5. The heat pump system of  claim 4 , wherein the operating parameter is a target temperature of an air flow at an intake section of the heat pump system, and the control circuitry is configured to:
 determine a temperature of the air flow at a discharge section of the heat pump system while the reversing valve is in the first configuration; and 
 adjust the position of the modulating valve to modify the temperature of the air flow at the discharge section to approach the target temperature. 
 
     
     
       6. The heat pump system of  claim 4 , wherein the operating parameter is a target humidity of a supply air flow discharged from the heat pump system, and the control circuitry is configured to adjust the position of the modulating valve to reduce a humidity of the supply air flow such that the humidity approaches the target humidity. 
     
     
       7. The heat pump system of  claim 1 , wherein the first heat exchanger is configured to receive a combination of the first portion of the refrigerant and the second portion of the refrigerant while the reversing valve is in the first configuration. 
     
     
       8. The heat pump system of  claim 1 , wherein the first heat exchanger is an indoor heat exchanger, and the second heat exchanger is an outdoor heat exchanger. 
     
     
       9. A tangible, non-transitory, computer-readable medium comprising instructions, wherein the instructions, when executed by processing circuitry, are configured to cause the processing circuitry to:
 position a reversing valve of a heat pump system in a first configuration to direct refrigerant from a compressor of the heat pump system toward a modulating valve of the heat pump system in a modulating reheat mode of the heat pump system; 
 adjust a position of the modulating valve to an intermediate position of a plurality of intermediate positions in the modulating reheat mode, wherein the plurality of intermediate positions is between a first position of the modulating valve and a second position of the modulating valve, and wherein, in each intermediate position of the plurality of intermediate positions, the modulating valve is configured to direct a first portion of the refrigerant through an outdoor heat exchanger of the heat pump system and to direct a second portion of the refrigerant through a reheat heat exchanger of the heat pump system in parallel with one another; and 
 position the reversing valve in a second configuration to direct the refrigerant from the compressor toward an indoor heat exchanger of the heat pump system in a heating mode of the heat pump system. 
 
     
     
       10. The tangible, non-transitory, computer-readable medium of  claim 9 , wherein the instructions, when executed by the processing circuitry, are configured to cause the processing circuitry to:
 adjust the modulating valve to the first position to block flow of the refrigerant to the reheat heat exchanger; and 
 adjust the modulating valve to the second position to block flow of the refrigerant from the reversing valve to the outdoor heat exchanger. 
 
     
     
       11. The tangible, non-transitory, computer-readable medium of  claim 9 , wherein the instructions, when executed by the processing circuitry, are configured to cause the processing circuitry to maintain the reversing valve in the second configuration and position the modulating valve to block flow of the refrigerant from the outdoor heat exchanger to the reheat heat exchanger in the heating mode of the heat pump system. 
     
     
       12. The tangible, non-transitory, computer-readable medium of  claim 9 , wherein the instructions, when executed by the processing circuitry, are configured to cause the processing circuitry to operate a fan to direct an air flow across the outdoor heat exchanger to maintain flow of the refrigerant from the outdoor heat exchanger toward the indoor heat exchanger above a threshold flow rate in the modulating reheat mode. 
     
     
       13. The tangible, non-transitory, computer-readable medium of  claim 12 , wherein the instructions, when executed by the processing circuitry, are configured to cause the processing circuitry to operate the fan based on a pressure of the refrigerant, a temperature of the refrigerant, a flow rate of the refrigerant, an ambient temperature, or any combination thereof. 
     
     
       14. The tangible, non-transitory, computer-readable medium of  claim 9 , wherein the instructions, when executed by the processing circuitry, are configured to cause the processing circuitry to adjust the position of the modulating valve to modify a temperature of a supply air flow to approach a target temperature, to modify a humidity of the supply air flow to approach a target humidity, or both. 
     
     
       15. The tangible, non-transitory, computer-readable medium of  claim 14 , wherein the target temperature comprises a temperature of a return air flow entering the heat pump system, a temperature of a space conditioned by the heat pump system, an ambient temperature, or any combination thereof. 
     
     
       16. A heat pump system, comprising:
 a refrigerant circuit comprising a compressor, an indoor heat exchanger, an outdoor heat exchanger, a reheat heat exchanger, a modulating valve, and a reversing valve, 
 wherein the reversing valve is configured to receive refrigerant from the compressor and adjust between a first configuration to direct the refrigerant from the compressor toward the modulating valve and a second configuration to direct the refrigerant from the compressor toward the indoor heat exchanger, 
 wherein the modulating valve is configured to apportion the refrigerant received from the reversing valve between the outdoor heat exchanger and the reheat heat exchanger, and 
 wherein the refrigerant circuit is configured to direct a first portion of the refrigerant from the modulating valve to the outdoor heat exchanger and to direct a second portion of the refrigerant from the modulating valve to the reheat heat exchanger in parallel with one another. 
 
     
     
       17. The heat pump system of  claim 16 , comprising control circuitry configured to control operation of the reversing valve and the modulating valve, wherein the control circuitry is configured to:
 position the reversing valve in the first configuration to operate the heat pump system in a modulating reheat mode; and 
 control the modulating valve to adjust a first amount of the first portion of the refrigerant directed to the outdoor heat exchanger relative to a second amount of the second portion of the refrigerant directed to the reheat heat exchanger in the modulating reheat mode. 
 
     
     
       18. The heat pump system of  claim 17 , comprising a fan configured to direct a supply air flow across the indoor heat exchanger and the reheat heat exchanger, wherein the indoor heat exchanger is configured to place the first portion of the refrigerant and the second portion of the refrigerant in a heat exchange relationship with the supply air flow to cool the supply air flow, and the reheat heat exchanger is configured to place the second portion of the refrigerant in a heat exchange relationship with the supply air flow to heat the supply air flow in the modulating reheat mode. 
     
     
       19. The heat pump system of  claim 17 , wherein the control circuitry configured to:
 determine a first temperature of a return air flow in the modulating reheat mode; 
 determine a second temperature of a supply air flow in the modulating reheat mode; and 
 control the modulating valve to apportion the refrigerant received from the reversing valve between the outdoor heat exchanger and the reheat heat exchanger to modify the second temperature to approach the first temperature in the modulating reheat mode. 
 
     
     
       20. The heat pump system of  claim 16 , wherein the refrigerant circuit comprises a conduit system extending between the indoor heat exchanger and the outdoor heat exchanger, wherein the conduit system comprises a first conduit and a second conduit arranged in parallel with one another, the first conduit comprises a check valve configured to enable flow of the refrigerant from the outdoor heat exchanger toward the indoor heat exchanger, and the second conduit comprises a valve configured to adjust between a first position to enable flow of the refrigerant between the indoor heat exchanger and the outdoor heat exchanger and a second position to block flow of the refrigerant between the indoor heat exchanger and the outdoor heat exchanger.